Test a few different sizes, even in non-extensive mode. In particular, 5 keys in a 5 slot store is important.
Use the constant for the number of probes.
IPConverter: optimise decodeBase85
Restore old sanity check
Sanity checks for IP-to-country decodeBase85
IPConverter: optimise readRanges
Detect when the IP to country database file is corrupt, set a flag to avoid reading it again.